1. Field of the Invention
The present invention relates, in general, to building construction tools, and in particular, to fastener driving tools for driving staples and nails and the like through cap washers.
2. Description of Related Art
It is often desired to use plastic cap washers to hold down roofing paper and so-called building wrap tar paper. Well-known solutions for this problem include providing plastic cap washers in bulk, each having a nail pre-inserted through the plastic cap washer, and a hammer is then used by a construction worker to pound the nail through roofing paper or tar paper wrapping and into a building. Application of such plastic cap washers to hold down roofing paper or tar paper wrapping is manual, tedious, and slow.
Automatic nail and staple guns, powered by compressed air or electricity, are used, for example, to attach roofing material, such as tarpaper, to the roof of a house. A generally fat cap is often used with each nail. A nail penetrates the cap and the tarpaper and protrudes into the underlying roof structure, attaching the roof surface. One example of such caps is disclosed in Bruins, U.S. Pat. No. 5,407,313 (issued Apr. 18, 1995).
Typically, an operator must manually place and hold a cap under the nose of a nail gun and then trigger the gun to drive a nail through the cap into the roof structure. The manual placement of caps presents a serious safety hazard to the operator because the operator's hand is close to the nose of the gun. In addition, manual placement of caps is time-consuming and inefficient. Another way the caps are made is with the nail already pressed through the center of the cap. One example of such caps is disclosed in Schwingle, U.S. Pat. No. 6,010,291 (issued Jan. 4, 2000). The installer of the cap must take each cap/nail and hand bang them on to the work surface with a hammer. This is very time consuming and difficult, not only hard on the back but hard on the fingers.
A cap feeding device may be employed to reduce the risk associated with manual placement of caps and to improve the efficiency of the roofing operation. The cap feeding device automatically places a cap under the nose of a fastener gun, and then the gun drives a nail through the cap and into the underlying structure.
Prior art cap feeding devices generally include a cap magazine and a base having an elongated channel. The base extends between the cap magazine and a position under the nose of the fastener gun. It shall be understood that the term “fastener gun” is used herein to indicate staple guns, nail guns, and similar construction tools for shooting a fastener, all of which can be used to affix caps by a construction worker. Caps are fed into the channel of the base from the cap magazine and pushed or pulled into position under the nose of the fastener gun. When the gun is triggered, a nail penetrates and dislodges the cap under the nose of the nail gun and protrudes into the underlying structure. The feeding of the caps under the nose of the nail gun is coordinated with the ejection of the nails through the nose of the nail gun, so that a cap is placed under the nose of the gun before the gun is triggered to expel a fastener.
Such prior art cap feeding devices have a number of drawbacks. For example, prior art cap feeding devices are generally heavy, putting additional stress on the operator's hand holding the fastener gun. Also, many prior art cap feeding devices can only be installed close to the front end of a fastener gun, making the fastener gun not only heavy but also unbalanced with most of the weight placed at the front end of the gun. This makes the nail or staple gun difficult to handle and may put stress on the operator's hand and wrist. In addition, with so many components placed at the front end or side of the tool it is difficult to see the position of the nose of the gun, making a precise placement of the nail difficult.
The conventional cap feeding devices are installed close to the front end of the gun because designers need to place a conventional cap magazine close to the nose of the gun to reduce the weight of the cap feeding device. The reason is that in many devices a cap is pushed directly from the cap magazine to a position under the nose of the gun. Thus, if the cap magazine is far from the nose of the gun, a long shuttle (with a correspondingly long reciprocating stroke) is needed to push a cap from the magazine into position under the nose of the fastener gun through the channel of the base. In addition, an actuator, such as an air cylinder, with a long displacement stroke, is also needed to drive the shuttle. The displacement stroke of the actuator should be about the same as the distance between the cap magazine and the nose of the fastener gun. A long shuttle and actuator increase the weight and size of the cap feeding device. With the cap feeding device placed near the nose of the gun, the shuttle and actuator, and thus the cap feeding device, can be made lighter, smaller and less expensive.
It is therefore desirable to have an automated construction tool and method of using same that provides for easier installation of such plastic cap washers than has been heretofore possible in the prior art. It is further desirable to have a lightweight cap feeding apparatus for use with a fastener gun that allows a magazine of caps and the cap feeding apparatus to be placed very close to the nose of the gun.